# std::filesystem::relative, std::filesystem::proximate

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< cpp‎ | filesystem

Defined in header `<filesystem>` |  |
path relative( const std::filesystem::path& p, std::error_code& ec ); | (1) | (since C++17)
path relative( const std::filesystem::path& p, const std::filesystem::path& base = std::filesystem::current_path() ); | (2) | (since C++17)
path relative( const std::filesystem::path& p, const std::filesystem::path& base, std::error_code& ec ); | (3) | (since C++17)
path proximate( const std::filesystem::path& p, std::error_code& ec ); | (4) | (since C++17)
path proximate( const std::filesystem::path& p, const std::filesystem::path& base = std::filesystem::current_path() ); | (5) | (since C++17)
path proximate( const std::filesystem::path& p, const std::filesystem::path& base, std::error_code& ec ); | (6) | (since C++17)

1) Returns relative(p, current_path(), ec).
2,3) Returns p made relative to base. Resolves symlinks and normalizes both p and base before other processing. Effectively returns std::filesystem::weakly_canonical(p).lexically_relative(std::filesystem::weakly_canonical(base)) or std::filesystem::weakly_canonical(p, ec).lexically_relative(std::filesystem::weakly_canonical(base, ec)), except the error code form returns path() at the first error occurrence, if any.
4) Returns proximate(p, current_path(), ec).
5,6) Effectively returns std::filesystem::weakly_canonical(p).lexically_proximate(std::filesystem::weakly_canonical(base)) or std::filesystem::weakly_canonical(p, ec).lexically_proximate(std::filesystem::weakly_canonical(base, ec)), except the error code form returns path() at the first error occurrence, if any.

### Parameters

p | - | an existing path
base | - | base path, against which p will be made relative/proximate
ec | - | error code to store error status to

### Return value

1) p made relative against current_path().
2,3) p made relative against base.
4) p made proximate against current_path().
5,6) p made proximate against base.

### Exceptions

Any overload not marked `noexcept` may throw std::bad_alloc if memory allocation fails.

2,5) Throws std::filesystem::filesystem_error on underlying OS API errors, constructed with p as the first path argument, base as the second path argument, and the OS error code as the error code argument.
1,3,4,6) Sets a std::error_code& parameter to the OS API error code if an OS API call fails, and executes ec.`clear`() if no errors occur.

### Example

Run this code

    #include <filesystem>
    #include <iostream>

    void show(std::filesystem::path x, std::filesystem::path y)
    {
        std::cout << "x:\t\t " << x << "\ny:\t\t " << y << '\n'
                  << "relative(x, y):  "
                  << std::filesystem::relative(x, y) << '\n'
                  << "proximate(x, y): "
                  << std::filesystem::proximate(x, y) << "\n\n";
    }

    int main()
    {
        show("/a/b/c", "/a/b");
        show("/a/c", "/a/b");
        show("c", "/a/b");
        show("/a/b", "c");
    }

Possible output:

    x:               "/a/b/c"
    y:               "/a/b"
    relative(x, y):  "c"
    proximate(x, y): "c"

    x:               "/a/c"
    y:               "/a/b"
    relative(x, y):  "../c"
    proximate(x, y): "../c"

    x:               "c"
    y:               "/a/b"
    relative(x, y):  ""
    proximate(x, y): "c"

    x:               "/a/b"
    y:               "c"
    relative(x, y):  ""
    proximate(x, y): "/a/b"

### See also

path (C++17) | represents a path (class)
absolute (C++17) | composes an absolute path (function)
canonicalweakly_canonical (C++17) | composes a canonical path (function)
lexically_normallexically_relativelexically_proximate | converts path to normal form converts path to relative form converts path to proximate form (public member function of `std::filesystem::path`)

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